Stephen Smalley wrote:
> On Fri, 2006-09-01 at 08:55 -0400, Paul Moore wrote:
>
>>Stephen Smalley wrote:
>>
>>>On Thu, 2006-08-31 at 12:20 -0500, Klaus Weidner wrote:
>>>
>>>>On Thu, Aug 31, 2006 at 08:57:05AM -0400, Paul Moore wrote:
>>>>
>>>>>Klaus Weidner wrote:
>>>>>
>>>>>
>>>>>>I was a bit surprised that a "s2-s2" process can connect successfully to
>>>>>>a "s3-s3" process, send it data, and select/poll(2) waiting for data.
>>>>
>>>>[...]
>>>>
>>>>
>>>>>>It works as expected the other way around, the s3 process gets an
>>>>>>immediate "connection refused" when trying to connect to the s2 process.
>>>>>
>>>>>This smells like a policy issue to me. Taking a quick look at the
>>>>>reference policy mls constraints (this is from a svn snapshot which is
>>>>>probably a month or two old, so it may have changed) I see the following
>>>>>constraint (unrelated types removed for clarity):
>>>>
>>>>It's a bit more complex now:
>>>>
>>>># the socket "read" ops (note the check is dominance of the low level)
>>>>mlsconstrain { socket tcp_socket udp_socket rawip_socket netlink_socket
>>>>packet_socket key_socket unix_stream_socket unix_dgram_socket
>>>>netlink_route_socket netlink_firewall_socket netlink_tcpdiag_socket
>>>>netlink_nflog_socket netlink_xfrm_socket netlink_selinux_socket
>>>>netlink_audit_socket netlink_ip6fw_socket netlink_dnrt_socket } { read
>>>>getattr listen accept getopt recvfrom recv_msg }
>>>> (( l1 dom l2 ) or
>>>> (( t1 == mlsnetreadtoclr ) and ( h1 dom l2 )) or
>>>> ( t1 == mlsnetread ));
>>>>
>>>># the socket "write" ops
>>>>mlsconstrain { socket tcp_socket udp_socket rawip_socket netlink_socket
>>>>packet_socket key_socket unix_stream_socket unix_dgram_socket
>>>>netlink_route_socket netlink_firewall_socket netlink_tcpdiag_socket
>>>>netlink_nflog_socket netlink_xfrm_socket netlink_selinux_socket
>>>>netlink_audit_socket netlink_ip6fw_socket netlink_dnrt_socket } { write
>>>>setattr relabelfrom connect setopt shutdown }
>>>> ((( l1 dom l2 ) and ( l1 domby h2 )) or
>>>> (( t1 == mlsnetwritetoclr ) and ( h1 dom l2 ) and ( l1 domby l2 ))
>>>> or
>>>> ( t1 == mlsnetwrite ));
>>>>
>>>>Based on that policy, I'd expect the constraint on "connect" to prevent a
>>>>l1=s2,h1=s2 process from connecting to a l2=s2,h2=s2 port. Am I
>>>>misunderstanding something or is the check mixed up?
>>>
>>>connect is a process-to-socket check handled entirely in the socket
>>>layer, i.e. can process A initiate a connection via socket S (where S is
>>>its local endpoint, not the peer). It isn't a check on the peer.
>>>
>>>recv_msg is likely the one of interest to you for NetLabel. You could
>>>separate out the mls constraint on tcp_socket to require equivalence for
>>>recv_msg in that case (overloading with old net controls is bad though).
>>
>>I know we've talked about this before and decided to stick with using
>>recv_msg ... does it make sense to introduce a new permission, say
>>nlbl_recv? Or do we just not care because of the secid reconciliation work?
>
>
> Hmmm...I thought that my guidance had been to use one of the obsoleted
> permissions in the socket class that was no longer in use by the kernel,
> like recvfrom (in common socket, different from association recvfrom).
You could very well be right (I'd have to check the archives). I
suspect I just got it confused with recv_msg. My mistake, but come on
guys, you couldn't have come up with some better more easily
distinguished permission names so people like me aren't as easily confused?
;)
Unless I hear any objections I'll see about making the change and
submitting it.
> Of course, if secmark is enabled, then recv_msg is likewise "obsoleted".
--
paul moore
linux security @ hp
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